The Federal Aviation Administration has invited pilots to help test modifications to the grounded Boeing 737 Max's flight-control software.

The FAA said Thursday it’s inviting Boeing 737 MAX pilots from around the world to participate in simulator testing "as part of the overall testing and validating of new procedures on the Boeing 737 MAX." The agency didn't specify how many hours of flight experience candidates should have, only that they must have some experience "at the controls of the Boeing 737 MAX." The FAA has yet to have "a firm schedule" for when these tests would take place, but said the tests would have to be done "before the aircraft is approved for return to service."